Partial cache line accesses based on memory access patterns

Abstract

According to a method of data processing in a multiprocessor data processing system, in response to a processor request to read a target granule of a target cache line of data containing multiple granules, a processing unit originates on an interconnect of the multiprocessor data processing system a partial read request that requests permission to read only the target granule of the target cache line. In response to a combined response to the partial read request indicating success, the combined response representing a system-wide response to the partial read request, the processing unit receives the target granule of the target cache line, supplies the target granule to a requesting processor core, and updates a coherency state of the target granule while retaining a coherency state of at least one other granule of the target cache line.